/Engine/Source/Editor/MovieSceneTools/Public/KeyframeTrackEditor.h
Templated construction function that can add a key (and potentially also set a default) for the specified channel and value
template<typename ChannelType, typename ValueType> static [FMovieSceneChannelValueSetter](API\Editor\MovieSceneTools\FMovieSceneChannelValueSetter) Create ( int32 ChannelIndex, ValueType InNewValue, bool bAddKey )